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Filename Latest commit message Latest commit date
Romain Perier 187697a454 drm: dw_hdmi: Don't rely on the status of the bridge for updating HPD
Currently, the irq handler that monitors changes for HPD and RX_SENSE
relies on the status of the bridge for updating the status of the HPD.
The update is done only when the bridge is enabled.

However, on Rockchip platforms we have found use cases where it could be
a problem. When HDMI is being used, turning off/on the screen or
unplugging/re-plugging the cable, the following simplified code path
will happen:

- dw_hdmi_irq() will be triggered by an HPD event, as the bridge is on
hdmi->disabled is false, then the handler will update the rxsense flag
accordingly.
- dw_hdmi_update_power() will be invoked with the mode
DRM_FORCE_UNSPECIFIED and rxsense == 1, so dw_hdmi_poweroff() will be
called and the PHY will be desactivated (its pixel clocks and TMDS)

[...]

- dw_hdmi_bridge_disable() will be invoked, the bridge will be marked as
disabled.

- dw_hdmi_irq() will be triggered by an HPD event, as the bridge is
currently disabled the HPD status won't be updated, so hdmi->rxsense
won't be changed. Even if the data part of the PHY is disabled, this
information coming from the HDMI Transmitter is correct and should be
saved.

[...]

- dw_hdmi_bridge_enable() will be invoked, the bridge will be marked as
enabled.
- dw_hdmi_update_power() will be called. When hdmi->force is equal to
DRM_FORCE_UNSPECIFIED the function will rely on hdmi->rxsense. If this
field has not been updated by the irq handler, it will be false and
DRM_FORCE_ON won't be put to hdmi->force.

Consequently, most of the time dw_hdmi_poweron() won't be called in this
use case, TMDS won't be re-enabled the PHY won't be re-initialized,
resulting in a "Signal not found".

This commit fixes the issue by removing the check for "!hdmi->disabled".
As already explained, even if the PHY is partially disabled, information
coming from HDMI Transmitter about HPD should be saved for a later use.

Signed-off-by: Romain Perier <romain.perier@collabora.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/143602/
2017-03-27 11:50:48 +05:30
arch Linux 4.11-rc3 2017-03-23 12:05:13 +10:00
block blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly() 2017-03-14 11:51:59 -06:00
certs
crypto net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
Documentation drm/todo: Add tinydrm refactoring ideas 2017-03-25 22:41:04 +01:00
drivers drm: dw_hdmi: Don't rely on the status of the bridge for updating HPD 2017-03-27 11:50:48 +05:30
firmware
fs NFS client fixes for 4.11 2017-03-17 14:16:22 -07:00
include drm/vblank: Remove DRM_VBLANKTIME_IN_VBLANK 2017-03-25 22:41:32 +01:00
init Change get_random_{int,log} to use the CRNG used by /dev/urandom and 2017-03-11 09:08:47 -08:00
ipc Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
kernel Linux 4.11-rc3 2017-03-23 12:05:13 +10:00
lib mm: convert generic code to 5-level paging 2017-03-09 11:48:47 -08:00
mm mm/swap: don't BUG_ON() due to uninitialized swap slot cache 2017-03-19 19:00:47 -07:00
net NFS client fixes for 4.11 2017-03-17 14:16:22 -07:00
samples Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
scripts Linux 4.11-rc3 2017-03-23 12:05:13 +10:00
security Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
sound scripts/spelling.txt: add "disble(d)" pattern and fix typo instances 2017-03-09 17:01:09 -08:00
tools Linux 4.11-rc3 2017-03-23 12:05:13 +10:00
usr
virt KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled 2017-03-07 15:44:08 +00:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Linux 4.11-rc3 2017-03-23 12:05:13 +10:00
Makefile Linux 4.11-rc3 2017-03-19 19:09:39 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.